Electrostatic Field Meter - Measures static charge and polarity on objects up to +-19.99 kV at a distance of 1 inch Chopper-Stabilized Sensor - Yields accurate measurements in both normal and ionized environments Dissipative Enclosure with 7 mm Ground Snap - Grounds the meter when held by a grounded operator or bonded to ground using the included ground cord Rotary Zero Knob - Sets the zero-reference point with finely tuned precision LED Range Indicator - Assists with placing the meter at the correct distance from the object being measured Hold Button - Allows the measurements to be retained for easy reading and extends battery life Ionization Test Upgrade Kit (19440) - Provides the accessories needed to test the balance (offset voltage) and discharge times of air ionizers Aluminum Conductive Plate Accessory (19441) - Allows the operator to measure the balance (offset voltage) of air ionizers NIST Calibrated with Certificate Included - Calibrated with accepted procedures and standards traceable to the National Institute of Standards and Technology